1. Progress on Sanitation and Drinking Water: 2015 Update and MDG Assessment (UNICEF and WHO, Geneva, 2015);
http://files.unicef.org/publications/files/Progress_on_Sanitation_and_Drinking_Water_2015_Update_.pdf
2. The Sustainable Development Goals Report 2018 (United Nations, New York, 2018);
https://unstats.un.org/sdgs/files/report/2018/thesustainabledevelopmentgoalsreport2018.pdf
3. Edzwald, J. K. & American Water Works Association. Water Quality and Treatment: A Handbook on Drinking Water 6th edn (McGraw-Hill, New York, 2011).
4. Sedlak, D. Water 4.0: The Past, Present, and Future of the World’s Most Vital Resource (Yale Univ. Press, New Haven, 2014).
5. National Primary Drinking Water Regulations EPA 816-F-09-004 (US EPA, 2009);
https://www.epa.gov/sites/production/files/2016-06/documents/npwdr_complete_table.pdf